//Given the head of a singly linked list where elements are sorted in ascending 
//order, convert it to a height balanced BST. 
//
// For this problem, a height-balanced binary tree is defined as a binary tree i
//n which the depth of the two subtrees of every node never differ by more than 1.
// 
//
// 
// Example 1: 
//
// 
//Input: head = [-10,-3,0,5,9]
//Output: [0,-3,9,-10,null,5]
//Explanation: One possible answer is [0,-3,9,-10,null,5], which represents the 
//shown height balanced BST.
// 
//
// Example 2: 
//
// 
//Input: head = []
//Output: []
// 
//
// Example 3: 
//
// 
//Input: head = [0]
//Output: [0]
// 
//
// Example 4: 
//
// 
//Input: head = [1,3]
//Output: [3,1]
// 
//
// 
// Constraints: 
//
// 
// The number of nodes in head is in the range [0, 2 * 104]. 
// -105 <= Node.val <= 105 
// 
// Related Topics 深度优先搜索 链表 
// 👍 534 👎 0


package leetcode.editor.cn;

import java.util.ArrayList;
import java.util.List;

//Java：Convert Sorted List to Binary Search Tree
 class P109ConvertSortedListToBinarySearchTree{
    public static void main(String[] args) {
        Solution solution = new P109ConvertSortedListToBinarySearchTree().new Solution();
        // TO TEST
    }
    //leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    List<Integer> list = new ArrayList<>();
    public TreeNode sortedListToBST(ListNode head) {
        while (head != null) {
            list.add(head.val);
            head = head.next;
        }
        return sort(0, list.size() - 1);
    }

    public TreeNode sort(int start, int end) {
        TreeNode root = null;
        if (start <= end) {
            int mid = (start + end) / 2;
            root = new TreeNode(list.get(mid));
            root.left = sort(start, mid-1);
            root.right = sort(mid + 1, end);
        }
        return root;
    }
}
//leetcode submit region end(Prohibit modification and deletion)

}